Strange election demographics

I noticed yesterday a curious pattern in the election posters on display in Priory Gardens, a residential street right by Highgate Tube station. At one end, closest to the station, are a few Labour Posters in people’s windows. At the other end of the street, there’s a cluster of Labour posters in a few people’s front gardens. In between, every election poster is for the Liberal Democrats. Is this just a statistical ripple of no significance, or should I infer that in this part of London there are more Labour voters at the end of streets than in the middle? Incidentally this is in the area described in this piece from the Independent, where the competition is essentially between Labour and the Liberal Democrats